1. Technical Field
The present invention relates to apparatus for acquiring, processing, and containing biologic fluid samples for analysis in general, and to apparatus for metering a known volume of biologic fluid in particular.
2. Background Information
Historically, biologic fluid samples such as whole blood, urine, cerebrospinal fluid, body cavity fluids, etc., have had their particulate or cellular contents evaluated by smearing a small undiluted amount of the fluid on a slide and evaluating that smear under a microscope. Reasonable results can be gained from such a smear, but the cell integrity, accuracy and reliability of the data depends largely on the technician's experience and technique.
In some instances, constituents within a biological fluid sample can be analyzed using impedance or optical flow cytometry. These techniques evaluate a flow of diluted fluid sample by passing the diluted flow through one or more orifices located relative to an impedance measuring device or an optical imaging device. A disadvantage of these techniques is that they require dilution of the sample, and fluid flow handling apparatus.
What is needed is a method and apparatus for metering a known volume of biologic fluid, one that does not require moving parts (e.g., one that can operate using capillary forces), one that is easy to manufacture, and one that is cost-effective.